Method for making polyolefin/filler films having increased WVTR

ABSTRACT

Films, made of polyethylenes and filers, and articles made therefrom greater WVTR than previously available films based on conventional Zeigler-Natta based polyethylenes. The polyethylenes are produced in a metallocene-catalyzed production process. The films may be made by a cast film process, and may be made in widely varying filler content, generally polyethylene to filler ratios of 30/70 to 70/30. The metallocene based polyethylenes when combined with filler also permit the extrusion of thinner films leading to lighter weight and softer films. The m-polyethylenes utilized for making such films typically have a Composition Distribution Breadth Index above 50%, a Mw/Mn below 3, and a Mz/Mw below 2. The films may be used advantageously in composite structures with fabrics (either woven or non-woven) to fabricate such articles as house-wrap

TECHNICAL FIELD

This invention relates generally to polyolefin films having greatlyincreased water vapor transmission rate, herein after denoted as WVTRand methods of making same. More specifically this invention is directedtoward filled polyethylene films having increased WVTR at a given fillerloading, and a given set of process conditions.

BACKGROUND

Preparation of films having good WVTR from highly filled polymers,usually polyolefins, are known. In the past a combination of apolyolefin, usually a polyethylene, with a filler, usually CaCO₃, whilevery useful and widely used as a film with good WVTR, usually incombination with non-woven polymers (for use in diapers, adultincontinence devices, feminine hygiene articles, housewrap composites,roofing materials and the like), have had some limitations that werewell known in the industry.

Among these limitations are a practical limitation in thickness (alsoexpressed as basis weight) in that conventional Ziegler-Natta catalyzedpolymers, more specifically linear low density polyethylene (LLDPE)highly filled film formulations could not generally be drawn down below3 mils. The most obvious problem with such a limitation is that the userof the film could not make a product utilizing a lower thickness film,meaning that the cost of the film (usually sold on a weight basis) mighthave been higher than the application necessitated. A less obvious issueis that at lower thicknesses, for the same density resin at the samefiller loading, the product would be relatively softer than higherthicknesses, an attribute of importance in any article that comes incontact with humans, such as apparel.

Another limitation of previous polyethylene/filler films is that for agiven filler loading, with conventional Z-N catalyzed polyethyleneresins, is WVTR, limited (on the upper end) by the amount ofpost-extrusion orientation that could be practically achieved.Additionally, the imperfections often found in conventional Z-N resinsand films, such as gels, made reaching and maintaining a high rate ofproduction difficult, and a high level of orientation might often leadto breaks, holes, or tear offs in the film leading to lower primeproduction rates.

Yet another limitation of the conventional Z-N filled and oriented filmsis related to both WVTR and production rates. Specifically, with a givenconventional filled polyethylene, to attain a certain WVTR, a certainfiller loading had to be used. In general, within limits, the higher thefiller loading, the more difficult to process ( the above referencedproduction problems such as large void creation and tear offs areexacerbated by a higher filler loading, as the film maker seeks tomaximize production rates).

U.S. Pat. No. 4,777,073 suggests a permeability and strength ofpolyethylene/filler combinations may be attained by combining a LLDPEdescribed as being made using a Zeigler-Natta or chromium catalysts,with fillers such as CaCO₃ present in the LLDPE from 15 to 35 percent byvolume which is equivalent to 34-62% by weight.

There is a commercial need therefore for a polyethylene fillercombination that will give a higher WVTR at a given filler loading, atan equivalent thickness. There is a similar need for a polyethylenefiller combination that can deliver equivalent WVTR at lower fillerloadings and can be made at a lower basis weight, than a conventionalZ-N polyethylene/filler combination.

SUMMARY

We have discovered that making a film from a polyethylene/fillercombination using a metallocene catalyzed polyethylene, surprisingly andunexpectedly provides the ability to achieve a substantially higher WVTR(at comparable filler loading and thickness), a lower thickness (orbasis weight) (at comparable filler loading and orientation), and canachieve an equivalent WVTR at lower filler loadings (improvingprocessability) when compared to conventional Z-N polyethylene/fillercombination.

The metallocene catalyzed polyethylenes (m-polyethylene) will have amolecular weight distribution (defined as the ratio of weight averagemolecular weight to number average molecular weight M_(w)/M_(n))generally less than 3, preferably less than 2.5.

The drawdown of a filled m-polyethylene will be more than 10, preferablymore than 20, more preferably more than 30 percent less than theultimate drawdown of a filled Z-N polyethylene, where the relationshipin the filled Z-N polyethylene between the filler amount and basisweight (minimum) for films follow the general equation:

W=2.10+0.380 (weight % CaCO₃)

where W is the minimum basis weight in g/m2 in the film.

The relationship is at constant draw (orientation transverse directionor TD) of 2.7:1, line speed 340 feet per minute (fpm). Form-polyethylene filled formulations the following general equationapplies:

W=3.07 +0.207 (weight % CaCO₃)

Additionally the water vapor transmission rate (WVTR) of a filledm-polyethylene is at least 10 percent greater, preferably at least 20percent, more preferably at least 30 percent greater than a filled Z-Npolyethylene, at the same filler loading and thickness (basis weight),where the Z-N polyethylene/filler WVTR is described by the equation:

WVTR=−10,900+320 (weight % CaCO₃)

where the WVTR is in g/m²/124 hours, measured at 37.8° C., 90% RH. Whilea film including a m-polyethylene and filler follows the generalequation:

WVTR=−9967+358 (weight % CaCo₃)

The relationship is at constant draw (orientation TD) of 2.7:1, linespeed 340 feet per minute (fpm).

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects, features and advantages of the present inventionwill become clearer and more fully understood when the followingdetailed description, and appended claims are read in conjunction withthe accompanying drawings, in which:

FIG. 1 illustrates the drawdown advantage of filled m-polyethylene overZ-N polyethylene with a plot of minimum basis weight in g/m2 versusfiller loading.

FIG. 2 illustrates the WVTR advantage of m-polyethylene versus Z-Npolyethylene in a plot of WVTR versus percentage of filler CaCO₃ both at2.7:1 draw ratio and 22 g/m² basis weight

DETAILED DESCRIPTION

Introduction

This invention concerns certain polyethylene/filler films that will havehigh WVTR and the ability to be drawn down to low basis weights andmethods for making same. Particularly useful in these films and methodswill be m-polyethylenes.

In certain embodiments of the present invention films of m-polyethyleneand filler can be made with lower amounts of filler and still attainsubstaintially the same WVTR as previously known and used Z-Npolyethylene/filer combinations (at higher filler loadings) are alsocontemplated. This invention further includes certain m-polyethylenes,their conversion into fabricated articles such as films, articles madefrom such films, and applications in which such articles having highWVTR combined with good physical properties are desirable. The resultingfilms, and film composites, (including coextruded and laminated films)have combinations of properties rendering them superior and unique tofilms or film composites previously available. The filled m-polyethylenefilms disclosed herein are particularly well suited for use in producingcertain classes of high WVTR films, consumer and industrial articlesusing the films in combination with for instance, polymeric woven ornon-woven materials. Such consumer articles include, but are not limitedto diapers, adult incontinence devices, feminine hygiene articles,medical and surgical gowns, medical drapes, industrial apparel, buildingproducts such as “house-wrap”, roofing components, and the like madeusing one or more of the films disclosed herein.

Additionally the films having increased WVTR of the present inventionmay also be used in metallized films with a high WVTR, according to thedisclosure of U.S. Pat. No. 5,055,338, fully incorporated herein forpurposes of U.S. Patent practice.

Housewrap

Fabrics suitably laminated to the breathable film in the housewrap ofthe present invention include any high strength fabric which can bebonded to the breathable film without adversely affecting the watervapor permeability or the resistance to air permeability of thebreathable film, i.e. the fabric must generally have a suitably openmesh to avoid substantialy blocking the micropores of the breathablefilm. The fabric may be woven of any suitable material, but ispreferably non woven polyolefin such as, for example, low densitypolyethylene, polypropylene, and preferably linear, low densitypolyethylene or high density polyethylene. The fabric should have anelongation (ASTM D1682) less than about 30%: an Emendorf tear strength(ASTM D689) of at least about 300 g, preferably at least about 600 g andespecially at least about 900 g: and a break load (ASTM D1682) of atleast about 15 lb/in., preferably at least about 25 lb/in., andespecially at least about 30 lb/in/ These fabrics are believed to beprepared from HDPE films having outer layers of ethylene vinyl acetatecoextruded on either side of the HDPE or heat seal layers. The films arefibrillated, and the resulting fibers are spred in at least twotransverse directions at a strand count of about 6010 per inch. Thespread fibers are then cross laminated by heat to produce a nonwovenfabric of 3-5 mils with about equal MD and TD strength. These fabricshave excellent strength properties in both MD and TD for reinforcing thebreathable film, an open structure to avoid substantially blocking themicopores of the breathable film when laminated thereto, and an outerlayer of ethylene vinyl acetate copolymer for heat sealability.

The fabric and the breathable film are laminated together to form thebreathable composite of the invention. The lamination may be effected byfacing the film and the fabric together and applying heat and pressure.The laminating temperatures to which the film and fabric are exposedshould be sufficient to achieve lamination, but should not be too highin order to avoid the flow of the film polymer into the microporousspaces and consequent reduction in water vapor transmissibility. In apreferred embodiment, the fabric is heated on a hot roller, preferablyat 200°-240° F., and then pressed, prefeably at a pressure of about50-100 psi, into contact with the unheated film to bond the fabric andfilm into laminate.

Preferred fabrics are commercially available under the trade designationDD1001, CC-2001 and CC-3001 CLAF nonwoven HDPE Fabrics.

In an embodiment of our invention, the filled m-polyethylene films, whenoriented after film formation, would surprisingly and unexpectedly havehigh WVTR when compared to a filled polyethylene film made usingpreviously available Z-N catalyzed polyethylenes. Following is adetailed description of certain preferred m-polyethylenes, films, orfilm composites made using these m- polyethylenes and articles made fromthe films or film composites, that are within the scope of the presentinvention. Those skilled in the art will appreciate that numerousmodifications to these preferred embodiments can be made withoutdeparting from the scope of the invention. For example, although filmsbased on low density m-polyethylenes filled with CaCO3 are exemplifiedherein, the films may be made using combinations of m-polyethylenes withother polyolefins and with other fillers or filler combinations. To theextent my description is specific, it is solely for the purpose ofillustrating preferred embodiments of my invention and should not betaken as limiting the present invention to these specific embodiments.

Production of the Films

Films contemplated by certain embodiments of the present invention maybe made utilizing m-polyethylenes, by processes including, blown andcast, prefered is a cast film process. In such extrusion processes, thefilms of the present invention can be formed into a single layer film,or may be one layer or more of a multi-layer film or film composite.Alternatively, the m-polyethylene films described in this disclosure canbe formed or utilized in the from a resin blend where the blendcomponents can function to modify WVTR, physical properties, draw-downsealing, cost, or other functions. Both blend components and functionsprovided thereby will be known to those of ordinary skill in the art.Films of the present invention may also be included in laminatedstructures. As long as a film, multi layer film, or laminated structureincludes one or more m-polyethylene/filler film layers having the WVTR,or draw-down, and the like of the film, and the M_(w)/M_(n), CDBI andthe like of the m- polyethylene , in the ranges described herein, itwill be understood to be contemplated as an embodiment of the presentinvention.

Polyolefin Component

The polyolefin component can be any film forming polyloefin orpolyolefin blend, as long as the majority of the polyolefin component isa polyolefin with the following features:

preferred more preferred most preferred Mw/Mn <3 <2.5CDBI >50% >60% >65% Mz/Mn <2

Generally these ranges dictate the use of a metallocene catalyzedpolyolefin, preferred is a m-polyethylene, preferably a linear lowdensity m-polyethylene with a density in the range of from about0.90-0.940, preferred 0.910-0.935, more preferred 0.912-0.925 g/cc.Densities referred to herein will generally be polymer or resindensities, unless otherwise specified.

There is a wide variety of commercial and experimental m-polyethyleneresins useful in the manufacture of films included in certainembodiments of the present invention. A non-inclusive list is foundbelow along with the general bulk resin properties as published:

TABLE A Melt Index/ Density Melt Flow Commercial Designation (g/cm³)(g/10 min.) Type Exceed ® 103 0.917 1.0 eth/hexene (now 350L65 or350D60)* Exceed ® 301 now 357C80* 0.918 3.4 eth/hexene Exceed ® 377D60*0.922 1.0 eth/hexene Exceed ® 109* 0.925 0.75 eth/hexene Exact ® 3028*0.900 1.2 eth/butene Exceed ® 357C32⁺ 0.917 g/cc 3.4 Exceed ® 363C320.917 g/cc 2.5 ECD-401 0.917 g/cc 4.5 Exceed ® 377D60 0.922 g/cc 1.0Exceed ® 399L60 0.925 g/cc .75 *available from Exxon Chemical Co.Houston, TX, USA ⁺The Exceed ® 357C32 is the same resin grade as theECD-112 and ECD-115 used in the experiments.

It will be understood that in general we contemplate that a large numberof m-polyethylenes will be useful in the techniques and applicationsdescribed herein. Included components: ethylene-1-butene copolymers,ethylene-1-hexene copolymers, ethylene-1-octene copolymers,ethylene-4-methyl-1-pentene copolymers, ethylene dodecene copolymers,ethylene-1-pentene copolymers, as well as ethylene copolymers of one ormore C4 to C20 containing alpha-olefins, diolefins, and combinationsthereof. A nonexclusive list of such polymers; ethylene, 1-butene,1-pentene; ethylene, 1-butene, 1-hexene; ethylene, 1-butene, 1-octene;ethylene, 1-butene, decene; ethylene, 1-pentene, 1-hexene; ethylene,1-pentene, 1-octene; ethylene, 1-pentene, decene; ethylene, 1-octene;1-pentene; ethylene 1-octene, decene; ethylene, 4-methyl-1-pentene,1-butene; ethylene 4-methyl-1-pentene, 1-pentene; ethylene,4methyl-1-pentene, 1-hexene; ethylene 4-methyl-1-pentene, 1-octene;ethylene, 4-methyl-1-pentene, decene. Included in the ethylenecopolymers will be one or more of the above monomers included at a totallevel of 0.2 to 6 mole percent, preferably 0.5 to 4 mole percent, orsuch mole percents consistent with the resin densities contemplated.

The resin and product properties recited in this specification weredetermined in accordance with the following test procedures. Where anyof these properties is referenced in the appended claims, it is to bemeasured in accordance with the specified test procedure.

TABLE B Property Units Procedure Melt Index dg/min ASTM D-1238(E)Density g/cc ASTM D-1505 WVTR g/m²/day described herein Gurley secondsdescribed herein

FILLER

Fillers useful in this invention may be any inorganic or organicmaterial having a low affinity for and a significantly lower elasticitythan the polyolefin component. Preferably the filler should be a rigidmaterial having a non-smooth hydrophobic surface, or a material which istreated to render its surface hydrophobic. The preferred mean averageparticle size of the filler is between about 0.5-5 microns for filmsgenerally having a thickness of between 1-6 mils prior to stretching.Examples of the inorganic fillers include calcium carbonate, talc, clay,kaolin, silica, diatomaceous earth, magnesium carbonate, bariumcarbonate, magnesium sulfate, barium sulfate, calcium sulfate, aluminumhydroxide, zinc oxide, magnesium hydroxide, calcium oxide, magnesiumoxide, titanium oxide, alumina, mica, glass powder, zeolite, silicaclay, etc. Calcium carbonate is particularly preferred for low cost,whiteness, inertness, and availability. The inorganic filler such ascalcium carbonate are preferably surface treated to be hydrophobic sothat the filler can repel water to reduce agglomeration of the filler.Also, the surface coating should improve binding of the filler to thepolymer while allowing the fuller to be pulled away from the polyolefinunder stress. A preferred coating is calcium stearate which is FDAcompliant and readily available. Organic fillers such as wood powder,and other cellulose type powders may be used. Polymer powders such asTeflon® powder and Kevlar® powder can also be used.

The amount of filler added to the polyethylene depends on the desiredproperties of the film including tear strength, water vapor transmissionrate, and stretchability. However, it is believed that a film with goodWVTR generally cannot be produced as is taught herein with an amount offiller less than about 20 percent by weight of the polyolefin/fillercomposition.

The minimum amount of filler is needed to insure the interconnectionwithin the film of voids created at the situs of the filler particularlyby the stretching operation to be subsequently performed on theprecursor film. Further, it is believed that useful films could not bemade with an amount of the filler excess of about 70 percent by weightof the polyolefin/filler composition. Higher amounts of filler may causedifficulty in compounding and significant losses in strength of thefinal breathable film.

While a broad range of fillers has been described at a broad range ofinclusion parameters based on weight percentages, other embodiments arecontemplated. For instance, fillers with much higher or much lowerspecific gravities may be included in the polyolefin at amounts outsidethe weight ranges disclosed, they will be understood to be contemplatedas embodiments of our invention as long as the final film, afterorientation has WVTR or drawn down similar to that described herein.

STRETCHING OR ORIENTING AND HEAT SETTING

Final preparation of a breathable film is achieved by stretching thefilled m-polyethylene precursor film to form interconnected voids.Stretching or “Orientation” of the film may be carried out monoaxiallyin the machine direction (MD) or the transverse direction(TD) or in bothdirections(biaxially) either simultaneously or sequentially usingconventional equipment and processes following cooling of the precursorfilm.

Film orientation may also be carried out in a tentering device with orwithout MD orientation to impart TD orientation to the film. The film isgripped by the edges for processing through the tentering device.

Stretching of melt embossed precursor films with a tentering device at afilm speed of about 200-500 per minute produces breathable films havingthe desired water vapor permeability. The resulting films had a greaterpermeability in the areas of reduced thickness in comparison to theareas of greater thickness.

A range of stretching ratios from 2:1 to 5:1 prove satisfactory for MDstretching with a ratio of 4:1 being preferred. A range of stretchingratios of 2:1 to 5:1 prove satisfactory for TD stretching with a ratioof 3:1 being preferred.

It is preferred that tension be maintained on the film during the heatsetting and cooling to minimize shrinkback. Upon cooling to ambienttemperature (i.e., room temperature) or near ambient, the holding forcemay be released. The film may contract somewhat (snapback) in the TD butwill retain a substantial portion of its stretched dimension.

Heat setting can be accomplished by maintaining the film under tensionin the stretched condition at the heat setting temperature for about 1-2minutes. Preferably, however, the heat setting and cooling is carriedout while permitting the film to contract slightly, but still understress. The controlled shrinkback of from 5 to 30%, preferably between15 and 25%, of the maximum stretched width has given particularly goodresults in eliminating storage shrinkage.

Properties of films produced from the resins

WVTR

In an embodiment of the present invention, certain films and articlesmade therefrom have higher WVTR than previously thought possible. TheWVTR of such films should be above 100 g/m²/day @ 37.8° C., 90% RH,preferably above 1000, more preferably above 3000 g/m²/day @ 25° C. Thiscan be seen in FIG. 2 which illustrates the WVTR advantage ofm-polyethylene versus Z-N polyethylene in a plot of WVTR versuspercentage percentage of filler CaCO₃.

In general the films of embodiments of the present invention will have amuch higher WVTR at the same filler loading than previously known Z-Npolyethylene based filled films. Specifically, the inventive films willhave a WVTR at least 10% higher than the WVTR of the comparative filmsdescribed by the equation:

 WVTR=−10,900+320 (weight % CaCO₃)

In another embodiment of our invention a m-polyethylene/fillercombination film can be stretched (oriented or tentered in the TD) lessthan a Z-N polyethylene combination film, and still achievesubstantially the same WVTR (at generally the same filler loadings).This is a significant advantage to a film maker because the greater theorientation, the greater the chance for a film imperfection to bemagnified, potentially causing a catastrophic failure (break).

It is not beyond the scope of embodiments of my invention to blend them-polyolefins to form the films of the invention with other materialssuch as other linear polyethylenes (HDPE, MDPE, LLDPE), low densitypolyethylene (LDPE), polypropylene (PP) (homopolymers and copolymers),polybutene-1 (PB), ethylene vinyl acetate (EVA), or other ethylene polarcomonomer copolymers and the like to fabricate useful articles. Suchpotential blend polyolefins may be conventional Zeigler-Natta catalyzed,chromium catalyzed, free radical initiated, and the like. However, theWVTR of the layer or layers intended to impart WVTR should generally bewithin limits disclosed above. Additionally, any blend component orcomponents additive or additives should be chosen such that the desiredWVTR of the film remains at or above the targeted or desired value. Anyblend should preferably contain a majority of m-polyethylene as thepolyolefin component, specifically greater than 50 weight percent,preferably greater than 60 weight percent, more preferably greater than70 (75?) percent, based on the total weight of the polyolefin

Definitions and Test Protocols

Value Units Definition or Test Density g/cm³ ASTM D-792 CDBI %*Definitions test determination contained in this application Molecularweight distribution none

TEST METHODS

Water Vapor Transmission Rate

The WVTR test measures the quantity of water vapor that is able to passthrough a film. A Mocon Permatran W-1 unit is used to measure WVTR bypassing a stream of dry air across the surfaces of the film. The dry airpicks up moisture that has passed, from wet pads underneath the film,through to the top surface.

The moisture level is measured by an infrared (IR) detector andconverted to a voltage which can be measured on a chart recorder. Theprocedure also includes:

a) Punching out a die cut hole in an aluminum foil mask,

b) Cutting off two opposing corners of the mask,

c) Peeling paper backing off of mask,

d) Cutting 2″×2″ squares of film and place them over the hole in themask,

e) Putting the paper backing back on the foil mask, then

f) Placing the masked sample in the test cell with the aluminum side up.The chart recorder reading is multiplied by 100 to give the WVTR value.

Gurley Porosity

Teleyn Gurley Model 4190 Porosity Tester with sensitivity attachment isused. With the procedure as follows:

a) Cutting a strip of film (˜2″ wide) across the entire web width,

b) Inserting a film sample to be tested between orifice plates,

c) Setting the sensitivity adjustment on “5”,

d) Turning the inner cylinder so that the timer eye is verticallycentered below the 10 cc silver step on the cylinder,

e) Resetting the timer to zero,

f) Pulling the spring clear of the top flange and releasing thecylinder,

When the timer stops counting, the test is completed. The number ofcounts is multiplied by 10 and the resulting number is “Gurley secondsper 100 cc”.

It will be appreciated by those of ordinary skill in the art that thefilms of m-polyethylene resins of certain embodiments of the presentinvention, can be combined with other materials, depending on theintended function of the resulting film.

Other methods of improving and/or controlling WVTR properties of thefilm or container may be used in addition to the methods describedherein without departing from the intended scope of my invention. Forexample, mechanical treatment such as micro pores.

DRAWDOWN

Embodiments of the present invention offer a significant and unexpectedimprovement in the ability for the formulations to be drawn down.Specifically, using conventional Z-N polyethylenes, a lower limit of2.5, more practically 3.5 mils has routinely been observed (as extruded)upstream, i.e. before orientation. By contrast, films of embodiments ofthe present invention, may be drawn down to a practical limit of 2 mils,providing a significant advantage in terms of either economics or acombination of economics and softness. The softness comes abvout due tothe decreased modulus of the lower thickness. Ultimate drawdown isdefined as minimum gage (or basis weight) before the onset of drawresonance at a given extruder rate (e.g., lb/hr).

The films of embodiments of the present invention will have ultimatedrawdown more than 20%, preferably 25%, more preferably 30% less thanthat of filled Z-N polyethylene which, from FIG. 2 has an ultimatedrawdown described by the general formula:

W=2.1+0.380 (weight % CaCO₃)

EXAMPLES

All polyethylene/filler materials were stabilized to diminish theeffects of extrusion.

Orientation of all the following examples was performed at a 2.7:1 drawratio, at 35° fpm, 150-220 °F. tenter temperature, 180-230° F. annealingtemperature.

Example 1-3

Examples 1-3 were fabricated from Escorene™ LL 3003.09 on a 6 inchMarshall & Williams cast extrusion line at normal processing conditionsprocessing conditions listed in Table 1a. Example 1 used a 50/50 weightratio of the polyethylene to CaCO₃, while examples 2-3 used a 65/35ratio of polyethylene to filler all films were subsequently oriented(TD) to three different basis weights as seen in Table 1.

Examples 4-9

Examples 4-9 were fabricated from Exceed™ ECD-112, under the sameprocessing conditions as examples 1-3. Examples 4-6 used a 50/50 weightratio of the polyethylene to CaCO₃, while examples 7-9 used a 65/35ratio of polyethylene to filler. All films were subsequently oriented(TD) to three different basis weights as seen in Table 2.

From the data in Table 1 for each of these examples run, it can be seenthat in Example 1 and 2; as filler level goes down, WVTR goes downdramatically, and as seen from example 3 a lower basis weight onlymarginally increases the WVTR of the film with a higher percentage ofpolyethylene. By contrast, from table 2 for examples 4-9, a much higherWVTR is achieved by the same filler loading and basis weight, than forthe films of examples 1-3, moreover, while a higher percentage ofpolyethylene in the formulation (examples 4-6 vs. 7-9) generates adiminution of WVTR, the percentage is far lower than that experiencedfor the Z-N polyethylene of examles 1-3 (95% reduction vs. 68%reduction)

Examples 10-15

Examples 10-15 are run as in Example 4-9, but the polyolefin componentwas a blend of LD-202 (12-MI, 0.917 g/cc low density polyethyleneavailable from Exxon Chemical Co.) and ECD112. As can be seen from thedata in Table 3, at the same basis weight Examples 4-6, and 7-9, thecorresponding films of Examples 10-15 had somewhat lower, but stillacceptable WVTR. Also of note is Example 15 which was the lowest basisweight attainable in this series (1-15) of examples (again orientationwas TD).

Examples 16-23

Examples 16-23 were extruded similar conditions to the previousexamples, into two (2) thickness of precursor (before orientation) film(4.5 and 6 mils) and oriented in the MD at 175° F. While WVTR resultsfor this set of examples appear to be substantially the same for bothmetallocene and Z-N polyethylenes, it is anticipated that when theorientation speed is increased, the m-LLDPE will show improved WVTR,over the Z-N-LLDPE, just as found in the TD orientation in examples1-15. The results are shown in Tables 4 and 5.

Examples 24-25

Examples 24 and 25 were extruded under substantially the same conditionsas the previous examples. Examples 24 is substantially the same inpolyethylene/filler content as example 4 and example 25 is substantiallythe same make-up as example 1.

Example 24 was drawn (oriented) at a 2.7:1 draw ratio, while example 25was drawn at a 3.8:1 ratio. These examples show that the m-LLDPE at alower (28%) draw ratio than the Z-N LLDPE, example 24 has generally thesame WVTR. The results are shown in Table 6.

While the present invention has been described and illustrated byreference to particular embodiments thereof, it will be appreciated bythose of ordinary skill in the art that the invention lends itself tovariations not necessarily illustrated herein. For example, it is notbeyond the scope of this invention to include additives with the claimedfilms or to blend resins to form the claimed films with other polymersor laminate the claimed films to other materials such as polymernon-wovens and the like. For this reason, then, reference should be madesolely to the appended claims for purposes of determining the true scopeof the present invention.

TABLE 1 ORIENTED FILM PROPERTIES LL 3003.09 Based Samples PROPERTIESExample 1 Example 2 Example 3 Basis Wt., g/m² 22.1 22.5 18.7 Yield,yd²/lb. 24.6 24.1 29.0 Emb. Cal., mils 1.17 1.13 .98 Gurley, seconds1137 Off-Scale Off-Scale WVTR, g/m²/24 5100 300 500 MD Tear, g 473 486386 TD 170° F. 9 8.5 7.8 Opacity, % 59.5 39.1 38.1 MD 10%, g/in 319.8417.9 392.0 MD 25%, g/in 352.1 429.6 414.1 MD Ult., g/in 456.2 494.4492.3 MD Elg., % 343.8 340.8 358.6 TD 10%, g/in 688.0 900.4 728.0 TD25%, g/in 1092 1391 1134 TD Ult., g/in 1725 2025 1842 TD Elg., % 127.1131.6 136.5 DR Limit g/m² 21.1 15.4 — The “DR Limit” also know as“Ultimate Drawdown” is the basis weight at which we first observed drawresonance. The DR probe was conducted with the fpm fixed at 340 and theextruder RPM reduced gradually until the onset of draw resonance.

TABLE 1 ORIENTED FILM PROPERTIES LL 3003.09 Based Samples PROPERTIESExample 1 Example 2 Example 3 Basis Wt., g/m² 22.1 22.5 18.7 Yield,yd²/lb. 24.6 24.1 29.0 Emb. Cal., mils 1.17 1.13 .98 Gurley, seconds1137 Off-Scale Off-Scale WVTR, g/m²/24 5100 300 500 MD Tear, g 473 486386 TD 170° F. 9 8.5 7.8 Opacity, % 59.5 39.1 38.1 MD 10%, g/in 319.8417.9 392.0 MD 25%, g/in 352.1 429.6 414.1 MD Ult., g/in 456.2 494.4492.3 MD Elg., % 343.8 340.8 358.6 TD 10%, g/in 688.0 900.4 728.0 TD25%, g/in 1092 1391 1134 TD Ult., g/in 1725 2025 1842 TD Elg., % 127.1131.6 136.5 DR Limit g/m² 21.1 15.4 — The “DR Limit” also know as“Ultimate Drawdown” is the basis weight at which we first observed drawresonance. The DR probe was conducted with the fpm fixed at 340 and theextruder RPM reduced gradually until the onset of draw resonance.

TABLE 2 ORIENTED FILM PROPERTIES For Exceed ™ ECD-112 Based SamplesPROPERTIES Basis wt g/m² Example 4 Example 5 Example 6 Example 7 Example8 Example 9 (Target) 22 g/m² 18.5 g/m² 15 g/m² 22 g/m² 18.5 g/m² 15 g/m²Basis Wt., g/m² 22.7 18.6 15.2 22.8 19.2 14.8 Yield, yd²/lb. 23.9 29.235.7 23.8 28.3 36.7 Emb. Cal., mils 1.23 .96 .81 1.24 1.03 .77 Gurley,seconds 216 159 127 3608 2140 1095 WVTR, g/m²/24 7950 8350 8450 25753675 4010 MD Tear, g 400 360 330 418 405 292 TD 170° F. 8.0 7.2 7.2 7.27.0 6.5 Opacity, % 66.2 62.3 59.1 51.6 48.3 44.9 MD 10%, g/in 299.6221.6 191.9 434.4 369.6 288.1 MD 25%, g/in 383.3 247.1 213.0 435.0 368.2285.3 MD Ult., g/in 496.9 323.6 296.5 501.6 411.9 304.7 MD Elg., % 327.5290.0 331.2 293.2 276.4 271.4 TD 10%, g/in 737.3 623.6 513.7 932.9 836.4678.6 TD 25%, g/in 1182 1003 851.8 1503 1342 1111 TD Ult., g/in 22611863 1574 2942 2689 2197 TD Elg., % 110.2 100.7 95.5 103.5 103.3 97.1 DRLimit g/m² 13.4 — — 10.3 — — The “DR Limit” is the basis weight at whichwe first observed draw resonance. The DR probe was conducted with thefpm fixed at 340 and the extruder RPM reduced gradually until the onsetof draw resonance.

TABLE 3 ORIENTED FILM PROPERTIES For samples based on Exceed ™ ECD-112blended with LDPE (LD-202) Example 10 Example 11 Example 12 Example 13Example 14 Example 15 37.5% ECD 37.5% ECD 37.5% ECD 56.3% ECD 56.3% ECD56.3% ECD 12.5% LD 12.5% LD 12.5% LD 8.7% LD 8.7% LD 8.7% LD 50% Calc50% Calc 50% Calc 35% Calc 35% Calc 35% Calc PROPERTIES 22 g/m² 18.5g/m² 15 g/m² 22 g/m² 15.0 g/m² 12 g/m² Basis Wt., g/m² 22.1 17.9 14.722.9 13.9 12.1 Yield, yd²/lb. 24.6 30.3 36.9 23.7 39.0 44.8 Emb. Cal.,mils 1.08 .99 .73 1.11 .70 .62 Gurley, seconds 1345 814 398 13,703 69303717 WVTR, g/m²/24 4800 5725 5925 950 1100 2350 MD Tear, g 98 90 85 371189 187 TD 170° F. 6.0 6.8 7 6 7 7 Opacity, % 59.7 55.6 51.2 50.6 40.337.7 MD 10%, g/in 361.3 304.6 255.4 472.8 331.2 277 MD 25%, g/in 391.6331.9 281.9 526.7 327.2 280.2 MD Ult., g/in 441.1 367.7 311.4 526.7352.8 296.5 MD Elg., % 163.2 137.3 103.2 259.8 202.8 177.2 TD 10%, g/in641.4 520.5 435.5 828.2 560 460.5 TD 25%, g/in 985 806.4 678.2 1294888.4 733.4 TD Ult., g/in 1578 1307 1197 2569 1912 1408 TD Elg., % 97.896.6 104.2 110.0 113.2 103.3 DR Limit g/m² <11.5 — — <6.4 — — The “DRLimit” is the basis weight at which we first observed draw resonance.The DR probe was conducted with the fpm fixed at 340 and the extruderRPM reduced gradually until the onset of draw resonance.

TABLE 4 175° F. Orientation 4.5 mil precursor film Example 18 Example 19Example 16 Example 17 50% CaCO₃ 50% CaCO₃ 50% CaCO₃ 50% CaCO₃ in in inECD-115 in ECD-115 LL3003.09 LL3003.09 4:1 Draw 6:1 Draw 4:1 Draw 6:1Draw PROPERTY Ratio Ratio Ratio Ratio Basis Weight, 54.7 34.5 54.8434.87 g/m² Embossed 2.43 1.93 3.29 2.79 Caliper, mils WVTR, 6100 79506500 7250 g/m²/24 hours Gurley Poro- 855 307 581 379 sity, sec/100 cc MDTensile 1094 1289 1084 1344 at 5%, g/in MD Tensile 2290 3034 2192 3041at 10%, g/in MD Tensile 4540 — 3774 — at 25%, g/in MD Tensile 7273 77255085 6135 at Break, g/in MD Elong. at 73.48 19.65 78.74 20.78 Break, %TD Tensile 201.1 102.4 178.7 104.9 at 5%, g/in TD Tensile 333.4 196.5293.4 184.7 at 10%, g/in TD Tensile 432.9 317.6 375.9 263.9 at 25%, g/inTD Tensile 568.6 318.1 482.8 276.9 at Break, g/in TD Elong. 350.1 241.7315.7 228.5 at Break, % MD Elmendorf 4 0 2 13.2 Tear, grams MD Shrink at13.5 17.6 10.5 16.0 170° F., % TD Shrink at −3.0 −3.1 −3.8 −2.9 170° F.,% Note: All samples oriented with a 15 fpm inlet speed, 190° F.annealing and 5% relaxation.

TABLE 5 175° F. Orientation 6.0 mil precursor film Example 22 Example 23Example 20 Example 21 50% CaCO₃ 50% CaCO₃ 50% CaCO₃ 50% CaCO₃ in in inECD-115 in ECD-115 LL3003.09 LL3003.09 4:1 Draw 6:1 Draw 4:1 Draw 6:1Draw PROPERTY Ratio Ratio Ratio Ratio Basis Weight, 63.19 47.95 65.7244.47 g/m² Embossed 3.30 2.68 3.20 2.55 Caliper, mils WVTR, 5450 75006250 7800 g/m²/24 hours Gurley Poro- 1151 363 541 282 sity, sec/100 ccMD Tensile 1336 1597 1370 1659 at 5%, g/in MD Tensile 2837 3691 27583686 at 10%, g/in MD Tensile 5598 — 4736 5025 at 25%, g/in MD Tensile9294 9934 6131 7479 at Break, g/in MD Elong. at 78.35 21.08 75.56 24.07Break, % TD Tensile 303.9 121.3 241.8 144.2 at 5%, g/in TD Tensile 473.4238.2 379.2 245.6 at 10%, g/in TD Tensile 589.7 421.6 473.8 326.9 at25%, g/in TD Tensile 820.8 464.8 634.7 356.5 at Break, g/in TD Elong.388.0 330.2 356.8 270.3 at Break, % MD Elmendorf 0 0 13.2 13.2 Tear,grams MD Shrink at 13 18 11.5 14.9 170° F., % TD Shrink at −3 −3 −3 −2.5170° F., % Note: All samples oriented with a 15 fpm inlet speed, 190° F.annealing and 5% relaxation.

TABLE 6 Example 24 Example 25 mLLDPE Z-N LLDPE 50% CaCO₃ 50% CaCO₃ 2.7:1draw 3.8:1 draw PROPERTY ratio ratio Yield yd²/lb 23.62 26.23 BasisWeight g/m² 23.13 20.85 Embossed Caliper mils 1.26 1.61 Gurley PorositySeconds/100 cc 251 230 WVTR g/m²/24 hours 7613 7688 MD Tensile at 5%Elg. grams/in 195.5 174.7 MD Tensile at 10% Elg. grams/in 269.1 272.9 MDTensile at 25% Elg. grams/in 301.7 321.8 MD Tensile at Break grams/in477.6 431.7 MD Elong. at Break % 346.4 293.7 TD Tensile at 5% Elg.grams/in 371.5 553.3 TD Tensile at 10% Elg. grams/in 622.0 980.4 TDTensile at 25% Elg. grams/in 932.9 1702 TD Tensile at Break grams/in1650 2162 TD Elong. at Break % 116.5 86.4 TD Shrinkage at 170° F. % 4.24.0

We claim:
 1. A method of preparing a laminate having good water vaportransmission rate (WVTR), said laminate including a filled film and afabric bonded thereto, said filled film including an effective amount offiller and having a water vapor transmission rate at least 10% higherthan the WVTR described by the equation: WVTR=−10,900+320(filler weight%) and the fabric having an elongation less than 30%, an Elmendorf tearstrength of at least 300 g, and a breakload of at least 15 lb./in., themethod comprising the steps of: (a) stretching said film to form astretched film; and (b) bonding said stretched film to said fabric, toform said laminate; (c) wherein said film is a polyethylene filmincluding a metallocene catalyzed polyethylene having a M_(w)/M_(n)<3,and a composition distribution breadth index greater than 60%.
 2. Themethod of claim 1 wherein said lamination is selected from the groupconsisting of heat lamination, adhesive lamination, extrusionlamination, mechanical bonding and combinations thereof.
 3. A process ofmaking a housewrap, comprising: a) mixing a polyolefin with a filler toform a polyolefin/filler mixture; b) extruding a film from thepolyolefin/filler mixture to form an extruded filled film; c) meltembossing the extruded filled film to form an embossed film having apattern of different film thicknesses; d) stretching the embossed filmto impart greater water vapor transmission rate; and e) melt bonding thestretched film to a nonwoven fabric comprising crosslaminated fibers ata temperature and pressure sufficient to bond the fabric and film toform a breathable laminate, wherein said polyolefin includes at least amajority of a metallocene catalyzed polyethylene having a M_(w)/M_(n)<3, and a composition distribution breadth index above 60 percent; andwherein the breathable laminate has a water vapor transmission rate atleast 10% higher than the WVTR described the equation: WVTR=−10,900+320(filler weight %).
 4. The method of claim 3, further comprising heatsetting the stretched film at a temperature above the stretchingtemperature and below the softening temperature of the stretched film.5. The method of claim 3, wherein the polyolefin is a copolymer ofethylene and a C₄-C₁₀ alpha-olefin.
 6. The method of claim 4, whereinsaid filler is calcium carbonate surface treated with calcium stearate.7. The method of claim 4, wherein the precursor film is melt embossedwith a diamond pattern.
 8. The method of claim 4, wherein thepolyolefin/filler mixture contains between about 30 percent to about 65percent filler by weight based on the total weight of said mixture. 9.The method of claim 3, wherein the fabric is a nonwoven polyolefinfabric having a heat seal layer.
 10. The method of claim 9, wherein thelamination comprises heating the fabric and pressing the unheated filmto the heated fabric.
 11. A method of making a housewrap, comprising: a)mixing a polyolefin comprising metallocene catalyzed polyethylene with afiller; b) cast extruding a precursor film of the polyethylene/fillermixture onto at least one melt embossing roller to form a melt embossedprecursor film having a pattern of different film thicknesses; c)stretching the melt embossed precursor film in the transverse directionto impart greater water vapor transmission rate in the areas of reducedthickness thereof in comparison to the areas of greater thickness, saidstretched melt embossed film having a water vapor transmission rate atleast 10% higher than the WVTR described by the equation:WVTR=−10,900+320(filler weight %); d) heating a nonwoven fabriccomprising cross-laminated polyolefin fibers and an ethylene-vinylacetate copolymer heat seal layer; and e) pressing the heated fabric tothe melt embossed precursor film at a temperature and pressuresufficient to bond the fabric and film to form a breathable laminatewherein said polyethylene has a M_(w)/M_(n)<3.
 12. The method of claim11, further comprising heat setting the stretched film at a temperatureabove the stretching temperature and below the softening temperature ofthe stretched film, and wherein said polyethylene has a M_(w)/M_(n)<2.5.13. The method of claim 11, wherein the polyolefin is a copolymer ofethylene and a C₄-C₁₀ alpha-olefin.
 14. The method of claim 11, whereinthe filler is calcium carbonate surface treated with calcium stearate.15. The method of claim 11, wherein the precursor film is melt embossedwith a diamond pattern.
 16. The method of claim 11, wherein thepolyolefin/filler mixture contains between about 30 percent to about 65percent filler by weight.
 17. The method of claim 11 wherein said filmhas a WVTR of at at least 20% greater than the WVTR described by theequation: WVTR=−10,900+320 (filler weight %).
 18. The method of claim 11wherein said film has a WVTR of at at least 30% greater than the WVTRdescribed by the equation: WVTR=−10,900+320 (filler weight %).
 19. Themethod of claim 1, wherein said laminate is a diaper.
 20. The method ofclaim 1, wherein said laminate is an adult incontinence device.
 21. Themethod of claim 1, wherein said laminate is a feminine hygiene article.22. The method of claim 1, wherein said laminate is a medical gown. 23.The method of claim 1, wherein said laminate is a surgical gown.